The Nervous System Flashcards
Study the basic breakdown of the nervous system, as well as the anatomy of the brain.
What are the two sub-systems of the nervous system?
The two sub-systems of the nervous system are:
- The central nervous system
- The peripheral nervous system
What are the physical components of the central nervous system (CNS)?
The brain and the spinal cord.
What is the physical component of the peripheral nervous system (PNS)?
All of the body’s nerves.
The peripheral nervous system is further sub-divided into the somatic and the autonomic nervous systems.
Define:
the somatic nervous system
The somatic nervous system is the sub-system of the PNS responsible for the voluntary control of muscle functioning and the detection of stimuli through the body’s sensory receptors.
Define:
the autonomic nervous system
The autonomic nervous system is the sub-system of the PNS responsible for subconscious, involuntary, visceral functions that maintain the body at a homeostatic state.
The autonomic nervous system coordinates activities such as digestion, heart rate, respiratory rate, salivation, excretion of urine, secretion of hormones, and sexual arousal.
Define:
the sympathetic nervous system
The sympathetic nervous system (SNS) is a sub-system of the autonomic nervous system that acts to prepare the body for physical or mental activity, particularly in the fight-or-flight response.
The SNS responds to major stressors by increasing heart rate, respiratory rate, blood pressure and perspiration, dilating pupils and bronchi, and decreasing digestion.
Define:
the parasympathetic nervous system
The parasympathetic nervous system (PNS) is a sub-system of the autonomic nervous system responsible for “rest and digest”, or the overall slow-down of the body’s functions in order to conserve energy.
The only body functions that the PNS augments are digestion and sexual arousal.
What two types of cells comprise the nervous system?
neurons and glial cells
Define:
a neuron
A neuron is the electrically excitable cell that comprises the nervous system and functions to process and transmit impulses through the body.
A neuron contains a cell body, dentrites, which gather and carry impulses to the cell body, and an axon, which carries information away from the cell body and towards other cells.
Define:
a glial cell
A glial cell functions to support the neuronal cells within the nervous system by providing nourishment, protection, and physical support.
There are many different types of glial cells, all with specific functions and locations.
Neurons could not function, or survive, without the support of glial cells.
Define:
a synapse
A synapse is the location where the axon of one neuron connects to the dendrite of the next.
The gap between neurons is called the synaptic gap, or cleft.
Synapses can either be chemical or electrical in nature.
Define:
an electrical synapse
An electrical synapse is a synapse in which the neurons are directly touching and are connected by small junctions that allow nerve impulses to pass directly from one neuron to the other.
Electrical synapses are not as common as chemical synapses.
Define:
a chemical synapse
A chemical synapse is a synapse in which the neurons do not actually touch, and instead communicate by sending chemical messengers (neurotransmitters) that bridge the gap between them.
Chemical synapses are more common than electrical synapses.
Define:
a neurotransmitter
A neurotransmitter is a chemical messenger that allows for the communication between neurons in a chemical synapse.
Neurotransmitters are released from the axon of the presynaptic neuron, diffuse across the synaptic gap, and attach to specific receptors on the dendrites of the postsynaptic neuron.
Define:
an action potential
An action potential is the technical term used to describe a nerve impulse.
Action potentials consist of a brief, reversible polarization of the neuron. The polarization then travels along the axon, allowing for the propagation of the impulse.
Define:
myelin
Myelin is a fat-like insulating sheath, made by glial cells, that surrounds the axons of neurons and dramatically increases the speed of the action potential propagation.